Far from an expert on this Sam - but I do know where to find the right info.
Quick summary: prevention in terms of repellent, covering up, vigilance and not using unpasteurised milk is a good starter. 6 cases of TBE in the UK since 2012 - all from Eastern Europe. Vaccine advised for travellers at risk (camping, hiking in forested areas). In terms of Slovenia then ticks will be active in August, particular areas are in the north provinces of Gorenjska and Koroska. If you want to have it you may need to get a shift on - multiple doses needed although possible to have them close together and still get a good level of protection.
If I was you I'd get your practice nurse or pharmacist to call NaTHNaC (now known as Travel Health Pro) for advice. They have reduced their opening hours - so time it between 9 and 11 or 1 to 2pm.
Steve