If it came about and we asked to join the EU we would have to agree to using the euro so much for the Scottish currency the SNP would like
This is just not true. EU lawyers have confirmed that if there is an on-going move towards Scottish Independence when/if Brexit is finalised then Scotland will not leave the EU but continue to be 'associate members' until an Independent Scotland is established , when it will become a full member with a seat at the top table. The Euro issue is a red herring. There is a requirement that new members should commit to joining the Euro but they cannot join until many conditions are met. Several current EU members have consistently failed to fulfill these conditions, year after year, but have continued to be full members of the EU without censure or penalties.
We know that Westminster wants to hang on to Scotland because of its wealth of natural resources e.g. surplus water, hydro, wind and wave power, more oil reserves (and reserves of coal which could be safely used in carbon capture power stations and the best fishing grounds. Not to mention lots of unused land, ripe for development. These resources would also be make Scotland a valuable member of the EU. Scotland's membership of the EU would be on an equal basis with all other member Countries, with a power of veto, a seat at the top table and a turn at leadership, unlike the position within the UK, where no MP representing a Scottish Constituency can ever be the PM under EVEL legislation and the only seat Scotland has at the top table ie. the Cabinet, is occupied by the bog useless David Mundell, Secretary of State for Scotland, who was only elevated to this position in 2015 because he was the one and only Tory MP elected in Scotland.