Hello Joseph -- You have a commemorative medallion, sometimes called a proof, with famous London tourist attractions. These are sold by merchants to UK visitors for a few US dollars or a few tens of US dollars. As far as I know, none are made of precious metal, although gold plating is an option (see the spiffy medallion in our secondary picture). Check eBay using a search on 'westminster abbey' to see representative items. Remember that eBay prices are only valid for items actually sold. Click on the 'sold listings' link first, then note the prices.
With no precious metal and with modern production dates, these pieces are worth very little on the secondary market. The medallion in our primary picture has been exposed to the elements and is worth less than $1 US dollar. If you have a pristine example in excellent condition, a coin dealer might pay a few dollars for it.