Ok I better start off by saying that I am a) a girl and b) know nothing about cars?

Dont all run away though because I need some help. Right I'll start off by saying that I have been given a 1996 (purpley-blue) golf GTI 2litre with 108k on the clock. It was a favour as my old car got towed away and you can't look a gift horse in the mouth ey? Anyway I noticed in the two days before I sent it in for a service that it cut out whilst driving (no I didn't stall) the engine just stopped (along with the power steering and brakes- scarey) so I sent it for a service and said all of this to the mechanic (who is a family friend) he did a service and did a full diagnostic test which brought up a problem with the distributor? so that was changed oh and some new shock absorbers because the previous owner had put giant super leggara wheels on and they were hitting the rims on every speed bump. So off I toddled thinking all was well. The mechanic informed me that the car, despite its age, is absolutely immaculate inside and out- no rust etc and was well impressed. So we went for a trip to Skipton and drove all day, no problems, the car is super fast blah blah.
Then yesterday I went to the local shop and nearly crashed at a junction because the car died mid turn. It took all of my strength on the brakes to stop in time (Im only 5'5'' girl remember). It literally just dies and starts coasting for no reason and starts up again when you turn it on and off again. I am really nervous to take the car to a garage of meaty oil heads who are going to take one look at me and clock up the quids in. So I have been looking online to try and educate myself on the problem- hence coming here! I have found loads of sites saying that it could be a relay ECU? 109 problem. So I went out with my torch and had a look. Oh and the electric windows decide when to work themselves and the imobiliser has been switched off due to problems (could be 109 too I believe) so I couldn't find a 109 there was a 30 there though.
Please somebody help. Is it right to have a black 30 relay there? Do you think this could be the problem? worth replacing first? dont laugh at my ancient car either by the way I LOVE it but I am afraid of killing myself and the kids at the moment. Could it be an ignition problem? I have come across that too online.
Oh and keep the terminology simple for my tiny brain.lol. I really appreciate ANY HELP. THANKS MILLIONS!!