I never had any significant congestion issues with them myself (I was there for over two years). There were a few times when things seemed a bit slow and/or high latency for half an hour or so, but had no prolonged issues.

I do recall that there were larger issues that affect some customers but not all, but IIRC they were taken seriously and quickly resolved (people who experienced the issues might feel differently, of course).

I've only been gone a month or so - unless something very drastic has happened I doubt they've gone badly downhill in that time.

That shows you have quite a number of LLU options as well as BT based ISPs, but it does not show what sort of service you can might expect. If you have a phone-line into the house (or know the number that was used last time the line was active, i.e. the phone number of the previous occupants) put it into http://dslchecker.bt.com/adsl/adslchecker.welcome and post the results here. If you don't have a line or don't yet know the number, use the postcode based checker instead.

Assuming your line is not too long (they won't touch anything beyond a certain length) I would probably recommend Be's "unlimited" product (or the cheaper "value" product if the line won't go faster than 12Mbit anyway. If you plan to upload much (i.e. any of you make much use of P2P) and you have a short line, you might consider the Pro product with "upload plus" (their name for AnnexM). Again without any line stats at all we can't say anything much more definite. Be are essentially unlimited, I found them to be reliable (I only moved away from them to get the better upstream speed offered by FTTC)

It looks like you might have FTTC available at the start of next year, so it would be worth trying to get a 6 month contract or less initially (Be offer a 3-month minimum on the middle and top products, others may offer similar and some will not so make sure you check when comparing plans). If you take a 12 or 18 month contract now it'll be expensive to switch over to FTTC in six months time if your exchange does get enabled in December.