And good discount of 8% and in some cases 10%! 
Lol
If you seriously think the same company that puts RHD GTI on hold due to lack of profit is going to offer S3 in UK at a reasonable price AND offer 8-10% discount you must be dreaming...
I know someone who has received 8% on his S3 ordered 3 weeks ago. That's another topic 
Yes, but not the new model (if it is really coming out soon...).
Going back to your options. I feel your pain. 3 months was long enough for me before September. If I were told I'd have to wait 7 months I'd not be buying. You're right to be looking somewhere else.
However. You can be looking at an S3 which is an old (er) technology. For me it was no go as I like toys (ACC, park assist, cornering lights, voice integration for RNS-510). You can get cheaper GTI in SEAT Leon but then it's a brand image problem...
Difficult one...