@alxndrhll - That's this forums version of an intervention. Solid advice though, cheers.
@C-Diddy - I had thought about doing it that way. You're right that at £55 a mag, having a 35 round one included, rather than 20 (which may be a step too far on the challenge scale), does make a difference.
Think I'll give the idea some breathing room and see how I feel in a while. Plenty of house and car stuff I need to outlay atm anyway.
Plus my next game is at South coast CQB and that's definitely one for the MP7!