Just thought I'd post my findings...it's worth shopping around.
My CO2 bottle was on 30 yesterday and it says not to let it below so I turned it off and phoned my local maidenhead aquatics (Woking). They said they do the refills but I'd have to take it in before Tuesday and then I can pick up my replacement after Wednesday and that'd it'd cost £10 for a bottle (and doing this would mean not being able to pick up my bottle till the weekend). I ummed and erred on the phone and he picked up on my hesitation and told me that _all_ MAQ have the same policy. Thankfully not believing them I called my next local (but it was engaged). So I tried Iver as I was over that way today...
They are MAQ too, and she said they did refills for £5.99 - and they have them in stock to do a swap. After I had hung up I had an afterthought that I hadn't mentioned gas or pressurized so maybe she was thinking of yeast refills
Anyway, popped in today, they had quite a few refills there! £5.99. What a bargain

I'm dead chuffed. I just need to coinside my CO2 running out with a visit to my parents

Gonna keep an eye on ebay for a spare bottle I think.
And even better...my boyfriend is getting fishy fingers...each time we go to LFSs he drools over the marine tanks

I think we'll be setting up a huge marine tank when we own our own place
