I'm thinking of collecting military medals of british campaigns. Is there anywhere I can get a copy of the medals awarded and the seniority of these awards

A comprehensive list of British medals and their seniority is available at https://military-medal.rickycasino3.com/the-order-of-wear.html. You might also like to look at the sites of some medal dealers to get a feel for availability, pricing and so on. Try http://www.medalsofservice.com.au for replica medals and https://military-medal.rickycasino3.com/dealer-directory/ to find dealers of original medals in your area.