A3 1.6 2000-W reg

Not great with cars, hoping someone who knows more can give me a bit of help!

Gear change 1-2 is always very difficult, other gear changes are also quite hard to get into. Occasionally getting into any gear is impossible, I've had to turn the engine off for 5 minutes, and after this break the gears are relatively smooth. Seems a little odd if a part is worn out and then works fine. Worth bearing in mind the gears are only smooth after the problem is so bad the car wont drive and I've had leave it for 5 minutes with the engine off.

Oil depletes very quickly, I've heard this can be a problem with the gearbox casing, so perhaps a new gearbox would resolve this problem?

It's pretty expensive, so would a gearbox repair be better? If it is what could the problem be?

Much thanks for any help or feedback.

Pheo