So update on this, dealer rang and said they couldn't find a leak, even after filling and letting it run for ages so they best they can do is top it up and see if it happens again.
They said even though seat assist jacked it up they had it on a actual ramp so they could be more thorough checking it.
Guess I'll just have to keep an eye on it over the next few days and see if it drops again
In the meantime Seat gave me a brand new Audi A3 1.6 TDI sline Stronic to drive about in, came with full led lights front and back along with the sweeping indicators.
My thoughts on it
The interior felt much more quality compared to the FR and its didn't half shift in dynamic mode, tech wise had mmi plus which although felt more up to date than the seat was less user friendly and I missed the touch screen, although sadly this didn't come with the virtual cockpit.
Couple of negatives, the car didn't feel as planted as the FR and I'd say standard suspension and ride on the FR feels a lot better.
Fuel tank was showing 435 miles range on a full tank which seems quite small.
The air vents reflect onto the side mirrors which is distracting and annoying.
The window switches were quite far back into the arm rests so you had to reach back to open a window, the FR has them in a much more natural position.
If I'd have to choose between a new A3 or a new Leon I'd have to go with the Leon, both good cars but think the Leon just edges it.