Given that you will be going to Ireland and Scotland, I would bring sufficient clothes and shoes to allow for the possibility--no, certainty--that your shoes and pant legs are going to be soaking wet on some days and will likely need a day to dry out between wearings. Waterproof or quick-drying shoes/pants will be a godsend. Also, both of those countries can be quite chilly at any time of year, so make sure you have enough warm clothes to deal with that. Layering is key.