Parking restrictions are determined by lines on the road, generally these are yellow, red or white. If there are no lines at all you can park on the side of the road without restriction. A solid yellow line means there are restrictions in place & you need to refer to the signs placed at regular intervals along the road to see what these restrictions are (e.g. no parking Mon-Fri 7am-10am, 4pm-6pm) If there are no signs, the general rule is no parking Mon-Sat between 8am and 6pm, Sundays and Bank Holidays have no parking restriction unless otherwise stated.
A double yellow line means no parking or waiting at any time. A single red line means no stopping or parking between certain times (see local signs), double red line means no stopping at any time. Red lines are generally only found in London or other major city centres.
Broken white lines marking parking spaces at the side of the road mean refer to the signs as parking / waiting times may be limited (e.g. Mon-Fri 30mins, no return within 1 hour). Zig-zag white lines mean no parking and are often found outside of schools and crossing points.
Paid parking is often by meter, ticket machine or in multi-storey car parks where you may be issued with a card ticket you have to feed into a machine when you return to your car and then pay the appropriate fee.
Enforcement of parking is done by traffic wardens who will photograph your car as proof you broke the law. You'll get a ticket but you can reduce the fine by paying quickly. If your car still isn't moved after a reasonable period of time it will be clamped or towed away. Fees for unclamping or reclaiming your car can be steep.
Blue Badge parking for the disabled is common in the UK. It allows you to park for free in all municipal car parks for up to two hours. It allows you to park in restricted parking areas for up to two hours as long as you're not causing an obstruction. There are plenty of parking spaces reserved for the disabled closer to where you may want to go.