It's very easy (ok it isn't actually that easy) - I did mine in a week including spending one evening messing with a heater, another evening to loosen the ball joints on the rack, a 3rd evening rebuilding the master cylinder with a new (FAULTY!!

) seal kit and a 4th evening to swap the engine backplate flywheel and clutch from 948 to 1098 (seemed a good idea at the time).
Therefore if you get a rack that already has the balljoints loose and don't do other jobs in parrallel it should be done in a weekend plus a couple of evenings.
The rack should be the easy bit - the Midget RHD rack is very similar to the Minor except the mechanism is reversed, so it makes a Minor LHD rack. Mine cost £2.70 on ebay.
The hard bit is to convert the gearbox. This is only 'hard' because it can be expensive! The clutch release arm comes out of the side of the box so you need to swap the 'front plate' (aka 'input shaft cover'). LHD ones are nearly impossible to get and a new one is £65+ etc.. from the traders. Make sure you get the correct one as the different gearboxes have different stud patterns (although you can convert the plate by drilling a few new holes... then you find the release levers are also different so you really regret not having the correct one... Doh!!). Alternbatively leave the gearbox alone and use a hydraulic clutch release system but make a pipe to go to the clutch M/C position on the left hand side.
Another interesting bit is the LHD accelerator pedal - without the correct parts you need to be very inventive.
All cars from 1955 onwards have the central dash - Easy peasy and nothing to do really (just don't convert a 54!!

)
So the basic procedure is:
0) check that the LH chassis leg has holes for the pedal shaft and mounting point for brake return spring. Replacement chassis legs often miss these out so beware! If not, then find a different car or get that sorted first.
1) Remove seats carpets and gearbox floor
2) Remove gearbox [unless doing hydraulic release system]
3) Remove brake m/c (lever torsion bar out of the way of bolts)
4) Remove pedal shaft and accelerator pedal
5) Remove steering column and steering rack
6) Remove rear axle brake pipes and flexi
7) Remove exhaust
8 ) Fit new pedal shaft bushes to LH chassis leg (clean out the holes first)
9) Fit M/C in LH chassis leg (lever torsion bar out of the way of bolts)
10) Refit rear brake pipes the other way round and make up a new mount for the flexi on the LH floor.
11) Either replace all the front brake pipes with new ones but put the T piece on the other side or just make up 1 new brake pipe (longer than standard) that stretches from the new M/C position to the original T piece position
12) Pedal shaft with Series 2 parts: swap to the other side and machine a new slot for the fixing pin to allow the shaft to be reversed . Minor 1000 : cut the clutch pedal off the pedal shaft and refit to the other chassis leg - you need to weld an extension piece on and make up a ingenious method to attach the pedal to the shaft.
Option 3 - get a LHD pedal shaft and pedal set!
13) Convert gearbox to have the LHD front plate and release lever on the other side - or convert to hydraulic clutch and use a longer pipe. [unless doing hydraulic release system]
14) refit gearbox - it only takes minutes when there is no steering rack

15) Using a mechanically able friend, fit the LHD rack to the car - don't bolt it up tight until you've fitted the column(Doh!!)
The LHD rack will only go on from inside left hand wheel arch - the RHD rack will only come out on the right hand side wheelarch - don't waste effort trying to do it all on one side (Doh!!)
16) fit steering column on LH and use it to align the rack. Then tighten the rack clamp bolts
17) Cut out the M/C cover hole from the gearbox floor. Cut out a new hole for the brake pedal etc.. Refit the gearbox floor using a M/C cover plate on both sides.
18 ) Refit exhaust
19) Either fit the LHD accellerator pedal or make new mountings for the existing pedal on the other side (complete with new hole in bulkhead near the petrol pump etc...) If making new mounting points make sure you leave enough room between the accelerator pedal and the other pedals (Doh!!)
So basically the minimum parts you need is a Midget RHD rack and the gearbox front plate (or hydraulic release system). You'll need to be pretty ingenius for the other bits or otherwise you need LHD pedal shaft, clutch pedal and accellerator pedal.
If you're exporting the car straight afterwards, then I'm not sure it's worthwhile to inform DVLA...
Enjoy!
ps - Any chance I can swap these tips for a nice quality video of 'Inside Out' BBC1 (West) on 30th Jan..... ;-)