At 5000' VFR, very little chance you'd get direct. There will be a lot of aircraft being vectored for approaches at that level.
Below 2000' you may have a shot of going through the zone, overhead the airfield and out the other side, as this usually won't conflict with instrument traffic.
Unfortunately the UK airspace isn't set up for expedient VFR flight, IFR takes priority. Once you're IFR and south of Edinburgh you typically get vectors all over the country and then on to the approach, the airspace really is very busy. VFR either has to fit in around that, or expect delays. You could plan as you go, asking well ahead the chances of a transit, and if it's clear there won't be on then go around.
I've flown full UK a few times, and generally used the west coast as it was easier to get a consistent straight line with no airspace in the way.