Yes, you would have a PPL with Multi Engine Land class rating. You can't use this license to fly a single-engined aircraft.
I doubt very much if it would work out cheaper. I don't know the current rate for renting a twin, but your £215 sounds reasonable. Do the maths - multiply this by the number of hours it'll take to get a PPL (let's say 55). The compare that to £100/hr multiplied by 55, and add on £215 times whatever the minimum for a multi-engine conversion is, plus a bit (can't remember what the minimum is off the top of my head). I think you'll find that doing your PPL on a single engine works out cheaper by quite some way. And that's ignoring the fact that you'd probably take a lot longer to get your PPL in a Seneca (I'm not sure if the minimum time is higher or not...)
That's quite apart from the safety aspect of a low-hours pilot flying a multi-engine aircraft. Could you really handle an engine failure on take-off on your first solo???
Also, do you know of any schools which will teach a PPL on a multi-engined aircraft? I'm sure there must be one somewhere, but I doubt if there are many.
Sorry to disappoint you, but I think this idea is a non-starter.
FFF
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