Its perfectly normal to be honest G.
Some heavy tin drivers keep there finger in the pie and still fly GA and glide and microlight as a hobby. And others flying is a job and they make a point of keeping as far away from any airport as they can during time off.
Now the chap is obviously looking for a school in the SE of England which will do a taster course over two days and following pilot tradition he wants it to be as cheap as possible while he has his lad for his weekend.
Now to the gentleman in question.
You have multiple choices what to do with your lad.
1. go for 4 trial flights which is to much to be honest because apart from different scenery they will all be the same he will become bored. Last kid I had who's dad had done the same we ended up doing circuits for 2.5 hours which the kid loved. For the last hour of it I was just a pax with the 14 year old kid doing everything to a solo standard. But it really screws with the syllabus and in hind sight I wouldn't recommend it.
2. Get a ppl 5 hour starter pack which will have 30-45mins trial flight in it but the rest will be formal lessons. But you won't be able to use it all in that weekend.
3. Forget spam cans and go to a microlight school. And give him a shot of weight shift. And maybe a 1 hour trial flight in a spam can to finish with.
4. But I would say that having it locked down to one weekend is going to give you huge stress because guaranteed the wx is going to be pants. And four hours flying for a kid in two days is tough going and its 50/50 if it will put them off (or maybe that's the plan
)
5. Get somewhere with a 4 seater and go for a 600 quid burger run with a land away. And you go in the back. From experience kids love dad being along and going somewhere via different routes keeps there interest up.
6. There is always the cross channel option down that end. But remember its a long way over water in a single.
As for which school I haven't go a clue but it ain't going to be cheap.
If it was me I would taken him for a microlight flight one day on a weight shift for an hour. Then the next go for a 4 seater flight with you in the back making suitable appreciative noises. It will also let you see if he has the knack or not and not be fed a line by the school. I would also keep stum about your job and then you can see if the school is one that you would want you lad to be trained at if you decided to take it further.