what do mean by new Software? the Sonos App and on which device?

Your Play:1s will work fine with the S2 software, only your Play:5 will be left behind on S1.

on iOS you may opt for SonPad for Sonos which lets you control both S1 and S2 compatible devices

 the new sonos sofware which my devices are not compatable with

Do you mean the S2 app, released quite some time ago? It certainly isn’t new. 
If you read the System Requirements for new devices such as the Roam you’ll see they are S2 compatible only. 
Your S1 and S2 devices will still work. And streaming services offer many stations including those from the BBC. 

However, The BBC has chosen not to allow any BBC Sounds to be streamed by anyone else, and only allow access from within their own app. This is why the only current way to get BBC Sounds streams to any other device that can’t run the BBC app, including Sonos, is to use something like AirPlay 2. 

@Airgetlam now I am a bit confused because I play without any problem BBC Radio 6 with TuneIn on my Sonos devices abroad (from UK)

Bruce was referring to the BBC Sounds radio-on-demand app, not live streaming of BBC radio stations, which is fine.

thanks for this clarification @John B 

Rather off-topic, but now that we are talking about BBC Sounds…

The BBC is now allowing the BBC Sounds app to be installed on many brands of TV and on streaming devices such as Amazon Firestick and Now TV. For anyone with a Sonos HT device (Beam etc) this provides a route in to your Sonos system for BBC Sounds. You can listen on other speakers by grouping them.

Edit: For iOS users, Airplay is the easiest way to play BBC Sounds on Sonos, as mentioned by Bruce.

would the BBC iPlayer do any good?

That is TV only, not radio. Until relatively recently the BBC would only allow the iPlayer app to be installed on a TV, but not BBC Sounds.