If I were starting down the road again I would look at AA TX200 / Walther LGU / HW 77 or 97. Pick the one that you feel fits / you like the feel of best. Normally club members are only too happy to let you try their guns and give advice.
No you definitely do not "need" a super tune to be competitive. Degrease, remove any burrs, a well fitting spring guide and top hat, relube... job done. Try a few different pellets and select the one (make and die batch) that groups best through your barrel.
Scopes are very personal (as our eyes are all different) but, for HFT good depth of field is important and a reticle that you personally like, again have a look through some that your club members are using.
If the bug really takes hold you can later think about a custom stock, more tuning etc. but, none of it will contribute very much compared to putting in the practice and building your knowledge and experience of range finding and reading the wind.
The Auld Alliance