i think i've only gone and blown it :(

I think ive managed to blow the head gasket on my k5 650,water in the sump(white creamy stuff in the oil) sounds and feels terrible and hasnt been running right for a while (also very naughty and overdue its 14500 service by about 1500 miles )....how much do you reckon im looking at to get this one fixed?

[Sid Squid]

What makes you think the head gasket has gone? Also check the seals on the water pump, a more common failure than head gaskets.
That said, are you sure it's not just that it's only had short journeys recently? This can make a mess of the oil in the present weather.

ah just somethin someone said made me think i had but the more people ive spoke to the less im believing that theory,ive done a mix of long and short journeys lately, rode 180 miles yesterday ....thanks for the tips, i'll give them a look in the morning

if you have a lot of water maybe you froze it and plug in head popped out.

I'd want to confirm whether it's water or not. The emulsion that forms with water can get very sticky and block oil ways with potential for further damage. I'd drain the oil and let it stand to see if it is water. If so, I'd stop using it until I resloved what was the cause.