I'm in the same position - a lot of my stalking is forestry but there are a few places where it is possible to lie up and have a spy and so I thought a spotting scope might be interesting to play with. Like you I didn't want to spend a lot of cash as for the most part I didn't need one but just fancied it as a diversion.
I went for an Optolyth 30X80 which I bought second hand off ebay. These scopes seem to do a little more than the 30X70s or similar and so see prices around £200 - £300 on ebay, based on my limited experience of watching a few and buying one. The 30X80 is a two draw scope whereas the others are, I believe, a single draw. I find the extra length useful for when I sit or lie back and rest the scope on my knee to steady it and I suspect this is why the 30X80s do a little more money than the other models. If you can try to get one with the leather case, mine didn't have a case but I'm going to have to buy something suitable or get something made up as it isn't easy to carry otherwise. They are nowhere near as long as the like of the Grays of Inverness spotting scope but it is a very specialised tool designed for use on the hill and second hand ones still make big money. The Optolyths have holes for a tripod mount if you need it.
In terms of optics I've been surprised at just how good the glass is but, of course, the key is to getting a steady rest and it has taken me a while of practise to find what works for me. I've now got a sort of system where I lie back against a lump, heather clump or what ever and rest the scope on my knee and can get a pretty good and relatively steady image. However, they do need a bit of light despite the big hole at the front so you will probably not get low light performance anywhere close to your binos. I've played with mine at night but for the purposes of long range deer spotting they really are very much a broad daylight proposition. Also because they draw open and shut they are not waterproof and also the suck air in and out each time you open and close them so they tend to get dirty inside. I believe that the Glasgow Binocular Repair Centre may have particular expertise in this area and if this turns out to be the case then I'm going to send mine off for a clean in the near future.
The other good thing about the Optolyths is that they are quite old and have probably lost all the money they are going to lose, so if you don't like it you can put it back on ebay with a reasonable expectation of getting most of your money back.
Yesterday I had the first real success with mine and lay out on the heather at the forest edge watching a reasonable sika stag feeding, at about 740 yards from me, along the tree line only for him to be joined by a very big stag. It was a fairly misty and overcast day and so less than ideal for long range observation but I was able to form a good opinion on the quality of both the stags in testing conditions.