To find a placement abroad as a part of your UK uni degree, then I'd recommend you take the following steps:
Speak with the placement co-ordinator in your department to find out if they know of particular programmes, company links who you could do the placement with. Also it's important to know if you need particular documents to be signed by the host company and if you have to complete specific curriculum/reports whilst you're away. If the department doesn't have programmes set up already, then you might have to then turn to outside agencies and/or network directly. If this is the case, things to consider are:
a) how do I find a placement which will offer a suitable training opportunity?
b) what are the visa requirements? Will I need to obtain a specific visa?
c) where will I live and how can I find accommodation?
d) will the host company offer me any training allowance?
e) remember to ask the host company for a training plan before heading to the placement, so you've an outline of the tasks/activities they're expecting you to do.
In some cases, it is possible to set up and arrange your own placement. Sometimes large companies advertise placement opportunities, these are competitive. To source your own position, then a web search, looking into job boards etc., is the way forward, plus making speculative applications. Sourcing a placement needs to be treated like finding a job in terms of the approach, cover letters, CVs and applications.
Many placement opportunities are not advertised and it's then a question of having the right contacts. Sometimes an outside agency can be a good option to assist as they will have a network of contacts, probably with SMEs, and able to source suitable placements for an industrial placement year. Also, they can normally help with documentation to get the visa. The downside of an external agency is that they'll probably charge a fee for their services and this can vary drastically between organisations. So, with this option, you've the trade off of time Vs money.
Good luck, whichever option of finding the placement you end up doing. Hopefully though, the Uni has some links to set you off on your search.