Most costs are included in the final OTR (On the road) price you see.
Only "incentive" is the £5000 government EV grant (which may well run out by the time purchase of the vehicle comes around. otherwise on company car schemes, the current Model S has a benefit in kind tax of 5% compared to other ICE vehicles of 15% or more (guesstimate)
Also, no congestion charge in london due to no emissions.
The government EV grant was just lowered in the last month or so to £4500. I imagine they'll lower it again before the release of the Model 3 once they realise what it's going to cost them purely on Model 3s.