Here's an update so far on my cheapo UK hosting adventure (I have no idea about uptime and shit):
* uk-cheapest.co.uk only allowed ancient version of wordpress. I wasted ages trying to get something up. Asked for a refund after a while.
* zyma.com Only just signed up but I like their customer service (answering quickly on a Sunday). Nice and cheap too- from £5 a year
* webhost.uk.net undecided yet, having an issue but it could be my fault. £15 a year with unlimited addon domains.
* bodhost.co.uk £20 a year with free domain name (probably unlimited addons). They tried to charge me for the domain name and didn't answer my question about how many addons are allowed. Undecided.
* ukcheaphosts.com ridiculously cheap at $12 a year including a free domain (unlimited addons). If my sites stay up then this is the cheapest/best option.
* falcoda.co.uk For 3 sites it cost £30 for 3 years with a free .co.uk domain name. Or it is £36 for 5 sites.
* csn-uk.net As recommended by others above. Costs a bit more at £3 per month. Only just signed up but seems fine so far, unlimited addons.
Please share if you have experiences with these or other super cheap hosting companies.