I looked into this whilst in the UK this year but if you've been out of the country over six years, give or take an exemption or two, then you cant play catch up. You have to have 30 years of contributions to be eligible (from 2010).

If you write to them, or call they are the most helpful part of the govt. No joke - they are so informative.

http://www.hmrc.gov.uk/nic/class3.htm

they are to some degree, well a UK pension would be paid over there, but to make voluntary contributions, you had to have paid contributions for 3 years prior to leaving the UK.

depends on your age obviously but for me I really dont think that there will be any state pension worth having when i get to the retirement age - which will probably be 100 by then!

I wonder if you move back would they allow you to pay double or 1.5 times the normal rate or something to be able to play catch up.
I haven't payed in enough to get a pension either. I only have probably 5 or 6 years of contributions, maybe 7 years at a pinch (I started work really young)
But to meet 30 years of payment, is an awful lot, what about Moms who spend 10 years having an looking after kids, before returning to work, and then maybe part time for a while. Thats what I've done here in US. Dh and I laugh, we get my SSI statement in the post each year and I should get enough for a pint of milk and the Sunday paper, in the US, even though I have really worked part time on and off for the last 20 years.