Hi,
It is possible to purchase a property here and not be a citizen etc and many people have done and continue to do so. It's like the same freedoms many people from many different countries have when wishing to purchase property in another country. The 'main' caveat is of course money. If you have a substantial amount to put towards the property cost, you can get a mortgage quite easily, prior to the financial mess the UK in particular is in, this figure was around the 25-45% range depending on which lender you spoke with etc. Nowadays, it's likely to be substantially higher (I've not kept up recently about it) and I'd envisage perhaps 50-70% perhaps? anyone in this sort of financial position will (relatively) easily be able to arrange financing for the rest of the funds.
It sounds as though you perhaps aren't in that level so finding lending and mortgages will be increasingly more difficult the less of a deposit you are able to stump up. Lending is currently difficult to get and I'd expect it to remain the same'ish over the next few years at least. I think the days of money being lent carelessly are over and stricter guidelines need to remain in place, however there's already talk of bringing back better rates for 5 and 10% deposit mortgages to citizens etc, it remains to be seen if foreign buyers will see a reduction to perhaps 35-45% of a property value in order to relatively easily secure a mortgage.
Of course, it does depend on where in the UK you do buy, but in general, vast swathes of the country are simply way beyond overpriced for those earning in the basic rate of tax and increasingly those earning the higher rate of tax as well, currently putting the idea/dream of home ownership totally beyond reach.
Do look to speak with various mortgage brokers and advisors, see if you can qualify for any incentives buy home builders if you are thinking of a new build and do as much research as you can regarding where to potentially look to buy and any issues to your legal situation and eligibility status etc.
Good luck!
cheers, DtM! West London & Slough UK!