Must say you have a good qualification and tangible work experience but you should note that PM is not yet that common in Nigeria in the social science sector which you belong, they mostly look for PM in Engineering or construction....so you might find it a bit difficult, nevertheless you will find it easier to get analyst or consultancy jobs in Nigeria. But the catch is that Esp for you UK trained you mite not be contented with the offer because you may want to compare it with what you can earn in UK by conversion, but you should note that we have different standard of living in both countries (like UK tax, heating bills etc) unlike Naija you have less of those...also the purchasing power is different.
Though I will not completely rule out the probability of getting a good PM job with nice pay in d social science sector but you must be ready to come back home and wait for the opportunity it mite not come fast fast as you may have to start from sumtin small OR be applying from England though must coy prefer you based in Naija when applying, OR you apply thru all dis international agency like globalcareers.com till you get one and relocate and in the mean time continue looking for a UK job but in that case pls after 6month without success in getting a professional job in UK, my opinion run bck hme b4 u get stucked in menial job and ur CV becomes more spacious as your last date of work was in 2009 and becomes more difficult, bcos no matter how hard e reach for naija u go get sumtn to kip d CV running.
Lastly, pray about it and have a focus, has I have exactly the same qualifications as you do and after some month in England without a job though my frends will kip on telln mi to stay behind do some hot jobs and sumtin will happen, I gave myself a deadline in England on not getting a job after d deadline passed, I moved to naija in feb, now I have an offer in PM with LNG (no connection in involved just online advert)
NB: what may work for you may not work for me depending on how focussed and determined you are and what your vision is and btw u and mi you CV needs polishing. All d best bro...God's blessings