Just looking around, seems that screwfix do a reasonable one for £56 that goes up to 130A, or one that does that little bit more at £71 for 160A - the next level up is £128 for a 250A so that's a bit of a step, but worth it if I'll use it!
Seems from what you guys have said that the 160A should be ample for all the tasks I'll need
Have you had any experience with Autodarken Masks? I know I'm looking at a response time as low as possible, with a range of darknesses of 9-13 or something, and Amazon do some for around £50 that look reasonable...
As usual, cheers for the info so far guys!