Hi Anna. A couple thoughts for you...
1. Are you still seeing your physiotherapist. It MAY be important to address more than just your foot. For example, hip strength and / or your back can play a role. Basically a thorough assessment should be done.
2. Orthotics are a very valuable addition to a rehab program. An arch CAN be built up too much however I am sure that your podiatrist assesses specific things with your foot and general alignment to ensure that is not the case. But...don't be afraid to ask questions and have him/her describe what they are changing and why with the orthotics.
3. I LOVE Soloman shoes and yes they are good shoes. However....I do have a narrow foot. There are lots of good shoes out there but the most important part when choosing them is to ensure they fit YOUR foot. Also ensure that they fit well with your orthotics. If you are in an area with a good specialty running store, the sales people are very knowlegable about feet and which shoes would best suit your needs. (This is the case in Canada anyway....I would think it would be the same in Scotland as running is a pretty universal activity)