Find out which political party controls your local area. Or if it's fairly evenly split then you have a choice of two. Sign up as a party member and go along to all the events and meetings. Offer to hand out leaflets and help at any fundraising stuff. Smile a lot and don't offer any opinions. Wear a plain shirt and a smart jumper from M&S. Assuming you don't have a major profile as a local sex monster, within a few weeks you'll be identified as "new blood" and some party elder will put their arm around you and earmark you for a future council seat. Keep up the effort of going to most meetings, smiling and not expressing any opinions.
You have to play the game but within 3 years you should have a Council seat and then you'll pick up between £6k and £15k a year for life plus a few expenses.
After about 5 years as a local councillor, assuming you keep smiling and not offering opinions, you'll be offered a chances as a county councillor (if it's a two-tiered system) so can double up on your annual cash return. At this point other civic roles in relation to public services governance/scrutiny committees will also be on your radar for some more pocket money.
After about 15/20 years you'll get to be Mayor (unless it's directly elected where you live) and then swan round, park for free and pick up even more expenses and a few foreign trips.
Keep it going and within 5 years of your ultimate death you'll have a road named after you and probably some part of a new swimming pool.
Lovely.