Safe commute from SW to SE London - HELP

I am a capable road & mountain biker and would like to start commuting to work - to save time, my health (a close family member has been diagnosed with a terminal illness and as such i need to avoid picking up any infections, that are rife on public transport), money and the environment...
My challenge is this: I plan to use my road bike & am happy riding circa. 20 miles each way and i know that it is obviously doable (as i have driven on occasion) I'm not prepared to do the journey entierely on the road as I predict that it'll be a matter of time before I have an unfortunate incident with a car, bus or lorry. In all instances I, the cyclist is likely to end up much worse off physically & financially. I'm trying to find a route that keeps me, as away from the main roads as possible (in an attempt to reduce my risk), so 'some' road, cycle paths & through parks.

I live in Sutton (SM6) & need to find a route to SE18 6RS.

Are there any reliable/ useful app?I've tried Kamoot, but have had limited joy.

If anybody is able to suggest an app or propose a route, I would be super greatful!

Thanks

There's a cycle route that basically follows the Wandle to Croydon. You can then use mostly shared/pedestrian bits through the centre and pick up the old railway track through Addiscombe Railway park to South Norwood. From there the NCN21/Waterlink way to Lewisham.

like this

https://www.google.com/maps/dir/SM6,+Wallington/Waddon+Ponds,+Croydon/Addiscombe+Railway+Park,+32+Burnham+Gardens,+Croydon+CR0+6NP/Royal+Arsenal,+London+SE18+6RS/@51.4601422,-0.0214731,12.71z/data=!4m36!4m35!1m10!1m1!1s0x4875fd63c8b66f75:0xb214a460ef75506c!2m2!1d-0.1460505!2d51.3626561!3m4!1m2!1d-0.1355015!2d51.3660648!3s0x48760774ed521f37:0x8f0ec496c565a0bd!1m10!1m1!1s0x48760714fa49cd97:0xb789f8eb79c9006e!2m2!1d-0.1203997!2d51.3699785!3m4!1m2!1d-0.096652!2d51.3741779!3s0x487607339c29ada7:0xf86f01be612faee1!1m5!1m1!1s0x487600dc1ac64bb3:0x36cfbecc930783f0!2m2!1d-0.0782003!2d51.3823315!1m5!1m1!1s0x47d8a8c75a924507:0xe4769b01a5ab2b3c!2m2!1d0.0770652!2d51.4932491!3e1

Excellent! I'll give that a go.

Also worth looking into cycle training that might well be provided by your borough. It will massively increase your safety.

#haveyouconsideredcycletraining