Temp for Keg

After 2 weeks in primary I just put my bitter into a keg. My problem is the only room I can store it in is the same room I fermented in i.e. it's a steady 21 deg C. I heard that you should keep it at fermenting temps for 2 or 3 days after kegging then move it somewhere cooler to mature but what are the consiquences of not doing this? Will it still be OK? if I leave it a little longer? Or should I try my best to find a cool place?

Can't you leave it outside in an insulated container.
Max temp at present is around 12c and it's not really freezing yet?

Where in the UK are you?

Thanks Orfy, i'm living down in hampshire at the moment so could put it in my shed. My only reservation is i'm going away tommorow until the 22nd Dec so if I leave my keg outdoors and temps drop between now and then I won't be able to rescue it, to be honest though after reading your reply I think i'm just worrying too much and will just go for it!