I may be wrong but I think it'd be very hard keeping up bilingualism. That's not to say you shouldn't keep up exposure and "tune the ear" but true bilingualism will be hard to attain if the child can't talk to people in that language.
I'd look on meetup for Spanish meetups - preferably with children. I know where I live (not UK) there's lots of English-speaking groups.
I've found a weekly 2 hour Saturday class. I'm looking for additional ways of keeping up the language. We will probably have an au pair again soon so she will have another opportunity to talk on a daily basis, but this is just until then.
I'll look for meet ups, but the difficulty will be that the children would naturally talk to each other in English.
You just need a VPN and download the channel's app, then stream it through your TV. Or YouTube through a Vpn and search for Spanish programmes. I generally do the latter now as my kids know what they like (generally other kids unwrapping toys!)
netflix gives the options for several kids tv shows for different audio. you have to search around, but they offer some in spanish, french, chinese etc. you just watch the show and check language audio options for each show. wish they made it easier to search via language!
The best way I have found to find which children programmes are available in other languages on Netflix is to use this site: unogs.com. Then go genre > all children Audio > whatever is your target language. You then have to filter by country (top middle in the blue box, not very obvious to find but it's there!).
It's not 100% accurate but much easier than checking each programme one by one!!
I am also trying to launch a website that would enable bilingual families to find others near them who speak the same language (and kids of similar age). More details here: www.crowdfunder.co.uk/bilingualkids, feel free to circulate!
Thanks for the tip @aurelieb. Will try that, it's a pain to check individually on netflix.
@hibbledobble I recently found a radio for kids in portuguese that is excellent - fun, informative - and have it in the background as much as I can. Or you can build a playlist on spotify and youtube kids? for the latter, better watch it with them fist to be safe. Are there any spanish playgroups near you? If not, why not start one? Post here on MN, or mush, for example. Good luck!
You can also use your iPhone as a remote for the apple TV if you own one and change the audio for languages (I realised that a few of the movies had French audio (esp disney!) and then it automatically changed the netflix audio as well).