Not totally sure your facts are right. You can claim theoretical motor mileage from residence to Birmingham Airport (nearest Trooping Airport to Scotland) and Motor mileage Paderborn/Hannover to destination. A tasty claim that should cover the ferry costs. I recommend the DFDS Newcastle Amsterdam crossing to keep the driving down. Amsterdam/Imjuden to BFG Northern areas is less than 4 hours. Pay a bit extra and go for a upgraded cabin and start your tour in Germany in style. Do not rely on UK HR for advice on postings to Germany; they have lost the knowledge base for this type of move. Do speak to your new Army HR gurus in Germany who are equally useless but do have experience of UK BFG moves. You can expect to claim for a couple of nights in a Hotel whilst you wait for your furniture to arrive. You are also entitled to 1x GYH(O) journey per year. MOD flight allowance of up to £195 per pax + mileage from residence to nearest airport and airport to destination UK. £800 for a fanily of 4, applicable against ferry costs also
Things aren't all bad
Enjoy