What does the House of Lords do?

Firstly, and most importantly, they hold the House of Commons to account. Secondly, they scrutinise draft legislation before it becomes law. And thirdly, they get to sit on the numerous subcommittees in the Lords. There are subcommittees covering all sorts of interesting topics and you can look at the aims and objectives of those committees and if you feel you've got something to contribute, you can apply to join. But equally, if you identify the need for a subcommittee around something that doesn't currently exist, you can start your own and you don't have to populate that committee with just other peers necessarily. You can invite external experts to join.