Hey y'all, I was wondering if anyone had any advice/warnings/comments/thoughts/etc. about an anniversary trip (10 years!) my partner and I are planning for late May. For context, I have been to the UK before a few years back but my partner has not. Also, I'm American and I've never driven anywhere but the US. This is the rough and very basic itinerary:

Day 0: Edinburgh

• Land in Edinburgh
• Check in to hotel
• Wander around the city

Day 1: Edinburgh

• Rent car
• Drive to St. Andrews
• Drive around in the Scottish Highlands

Day 2: Edinburgh > Redmire

• Drive south to a bed and breakfast in Redmire
• Check out the English countryside

Day 3: Redmire > Manchester

• Drive to Manchester
• Turn in car
• Check in to hotel

Day 4: Manchester > Bath

• Take a train to Bath
• Wander around Bath
• Stay at bed and breakfast

Day 5: Bath > London

• Take train to London
• Check in to hotel
• Do touristy things
• Eat a lot of food

Day 6: London

• Anniversary dinner

Day 7: London

• Wander around
• Eat a lot of food

Day 8: London

• Depart from Heathrow

I fully intend to add plan out the details and activities as we get closer, though I would be grateful for any recommendations for things to do or places to see. It's my partner's real first time out of the country and given it's an anniversary trip I wanted it to be mostly relaxed.

The first half or so of the trip is predicated on me, an American who drives on the right, driving good distances in the UK. I've plenty of experience doing long distance driving in the US, it's mostly the driving on the opposite side that concerns me. Is this recommended? Would it be better to just use rideshares or transit in the cities and take trains over the longer stretches between instead of a mini-roadtrip? Thanks y'all!

EDIT:
Thank you everyone for your thoughtful responses! I will try to get to as many as I can as soon as I can!

I am in Scotland for a little vacation with a friend, and am looking for recs! We are mainly in Edinburgh, but have a car and are open to just about anything! I don't really mess with touristy stuff, but am willing to try if you think its worthwhile! Also will be here for the rest of the week! We are planning on going to the gardens for sure, but other than that don't really have a whole lot planned. I would like to go to Galloway at night and see the milky way though. I love the scenery so I don't mind a short drive. Thanks :)