My battery has reached the end of its life

Its the 038 that was in when I still had a 1098 engine in the car and it always did struggle a little in the cold weather. I was thinking of putting a 063 battery in (41AH 360 Starting power) but have also seen a 063 with 52AH and 530 Starting power. Is this too much? Is it worth the extra 20 quid? The car is my only car and gets used generally 2-3 times a week so could do with the most reliable I can get. Any thoughts? Thanks
Will