Transition altitude
On my way up to Edinburgh on Friday night, I stopped in at Teesside for fuel. Leaving Teesside, I was cleared SVFR not above 2000 to the edge of their zone then given an RAS and the QNH. I climbed towards 4500ft, then set 1013 and adjusted to FL45 on the basis that, as it was night, I was IFR so should be flying quadrantal rules above 3000ft. On handover to Newcastle, I got given another QNH but, presumably because they weren't too busy, no particular route or height was specified. So I adjusted to 4500ft and transited Newcastle at that height.
Being passed QNH's confused me. I'm guessing its because the transition altitude at Newcastle is higher than 3000ft. How do I find out what the transition altitude is? Was I right to fly an altitude just because they gave me a QNH?