My reply though cannot be termed as legal with respect to your query, assuming that you are a hindu, you can easily get married with that foreigner in any temple which has a priest. Pay some money to the priest and he will get you married, exchange garlands, take a photograph of it, one exchanging garlands, another after exchanging garlands. Print a invitation and distribute it among friends/relatives etc, keep one invitation aside for proof of marriage. If the priest tells you to get mangalsutra, get it.
Is there any urgent requirement for showing proof of marriage? any property matter involved? you have not mentioned any of it in your query. If getting married is the only objective, follow the above method, right now and get the marriage registered later on.
These days marriage dont work, its very difficult to untie the knot after tying it. You are planning to tie the knot with a UK citizen, foreigners dont believe in marriage and stuff, and getting divorce for them is like changing clothes, are you sure about tying the knot with this guy? Think and take a step forward. 10 days later if you feel that you cannot live with each other, you will find it very difficult to untie the knot, ie get divorce. In other words, first do all the circus and get marriage registered, and later on when it wont work, do double circus to get away from each other. Its just a suggestion,, get married in UK as per norms there, if it work out fine, if it dont work out, divorce getting easy there unlike here in India.
Wish you happy married life in advance.