I cant do it. England's armies are of better quality, they have more money, better sliders and England has more soldiers/calavary. You could use a lot of inflation (straight from start of the game) and take out loans to buy more troops, but I imagine this would suck away your money really fast. Not to mention, there isn't enough man power to fight England's usual 15k army defences.
What usually happens early on in the game, is England will attack one of the minors in Ireland. You can: a) Ignore this and watch England slowly get stronger, thus Scotland will be more vulnerable. Or b) Find a strong ally. Proclaim a guarantee of independence on the Irish minors (before England starts a war against them, thats important) and wait. This plan will fail however, as England will probably still have Portugal as an ally and will go on attacking Ireland. England also has that massive navy, and there are no factions with the naval capabilities that can send armies into England, alive. Even France the most likely faction to get an alliance with and is also the strongest, can do nothing against England early on.
I suppose you could wait for France to make a reconquest against England and maybe France will force them to release some nations. But that doesn't happen often and England usually recovers from war with France very quickly.
A French-Scott alliance has to be timed right. If Scotland isn't allied to France, you miss out on the inevitable French reconquest and have to wait for a CB against England (which could take a while). Even worse is, if your not allied to France, who then will help protect Scotland against England?
Yes Scotland has the highlanders event that spawns 15k men. This however isn't a solution to England's armies to face.
One plan I think that could work however, is to wait for England to send half of its army to some far distant land, then coordinate a CB+Alliance and start the attack against them. But If you wait for too long to get a CB, England usually gets a CB of their own against Scotland. So time is of essence.
Whats your view on this? imo Scotland is a lose lose situation. Makes my TA England look like rubbish