Thanks everyone for the replies, offers of help and pms - I promise I'll get back to you all asap, just been one of those days (triplets being little terrors).
I'm planning on attempting a trip over to Leeds in a couple of weeks, was going to go have a look this weekend but dont think I'm up to it yet, and dont want to add anything to my tank for at least a couple of weeks. Am going to post on the emergencies board about some sort of blanket treatment for the tank, to kill of anything that might be causing probs. Dont know if it's even an option but I dont want to risk leaving it and waiting.
I've been told Pet City is really good - I do have some experience of them as that's where Rusty came from (Kathy picked him up for me in the summer) and he's been absolutely perfect health wise, he's grown from just over an inch and a half to the 6" he is now, and well - you've seen the pics, he's a really good rusty plec
Even if I do say so myself LOL.
Feeling a bit brighter today. Got plans for sooping up the tank to make it prettier and that - have got some bogwood hopefully coming in a fortnight (more bogwood that is, already have a 30" bit and a couple of 10"ish bits), and am planning on getting a new external to run alongside the FX5. Either another FX5 or I've seen a Resun 280 Cyclone on Ebay which has about the same spec as an FX5 but with an added UV steriliser, and it's cheaper than the FX5 too - I just hope there's some left on there when I get paid again (cant afford it this payday).
I was reading somewhere that a lot of bacterial infections are caused by bacteria around the gravel level - especially with plecs and their poo and things - and although I already gravel vac twice a week and that, I was wondering if in the future the tank would benefit from some clear up crew - maybe some cories or brochis? But the temp is high at 80f so dont think that's an option. Just something I was thinking of for the future (obviously not until I know the tank's safe).
Am keeping hold of the sevs for a couple of weeks (new home is willing to wait) so that I dont pass anything, if there is anything, on to anyone else.
Erm...that's it. But I'll get back to folks who've pm-ed asap