If you are interested in becoming an angel you can follow the links here for information on projects seeking backing which have web sites. You will find online investment proposals with budgets and recoupment schedules.
Alternatively you can write to The Society Of London Theatre and join the potential investors list, to whom their members can circulate investment proposals if they wish. Contact them at 32 Rose Street, London WC2E 9ET. Tel 020 7557 6700 Fax 020 7557 6799. The more established producers (with presumably a more reliable track record) will have a waiting list of people wishing to become investors, but as costs continue to escalate, will continually need new people.