If your car breaks down you have a choice of three numbers to call :-
Automobile Association:- 0800 887766
National Breakdown:- 0800 400600
Royal Automobile Club:- 0800 828282
All three are free numbers.
If you belong to a car breakdown assistance club in your own country, check what reciprocal arrangements if any it has with any of the above.
Should you be driving a rental car check with the hirers what action they require in the event of a breakdown/accident.
Generally, if your car breaks down, stay with it if this is practicable. Do not wander about on the road or hard shoulder. Ensure your hazard lights are flashing. If somebody stops, lock your doors from within and speak to them through the window - you do not take chances, particularly on motorways and quiet rural roads. They are almost certainly well-intentioned passers-by.
For your reassurance the AA claim that 80% of their call-outs are dealt with on the spot, and they are rightly proud of their record.
And just a reminder that in UK we drive on the left hand side, most urban speed limits are 30 mph, with 60 mph on normal non-urban roads and 70 mph on motorways. The British 'Copper' is very zealous when it comes to enforcing speed limits and take few prisoners.
Take a look at our Highway Code when you have a spare moment. It is well-written and could well give you a few tips.
.