Is that 300NM all in, or one way? If the latter then you could consider Berlin Tempelhof. Good excuse to get this airfield in your logbook before it closes in October.
I did the trip from Shoreham about 3 weeks ago: EGKA - EGMD (for cheap fuel) - KONAN and then more or less DCT EDDI
You get to travel through a variety of interesting airspace (B in Belgium, D in Germany), cross several FIRs and have the fun of hearing lots of accents on the radio.