Hi, there - congrats on your purchase. Yeah, there are quite few active S1 servers these days compared to S2 servers (which aren't as active as they used to, either).
However, there should be some servers during peak hours. At least Cargame.nl S1 server should be up with a number of active drivers...
Make sure that you've not enabled any filters on the host page (which might somehow filter out populated S1 servers).
As far as I am aware, LFS is built in a such a way that if, on a S2 server, the host configuration is set to match S1 limitation, it WILL work as a S1 server. Therefore, you would be able to join in if a server is setup in a simialr way (S1 cars, tracks etc.).