i rode it from seville to santiago in may. flew out on monday may 8. returned from santiago on friday may 26. so 17 days of cycling, no days off.
you could cut those days by buying your "credencial or Pilgrim Record" from the https://www.csj.org.uk
co-fraternity of st james in london. then you could save time by avoiding riding into seville and having to purchase it from somewhere there and then spending a night there, leaving Seville the next morning. Instead you could cycle away from the airport and head straight to Guillena which is in your direction. From the airport it is tricky to get out without using the autovia which is dual-carriageway road with masses of traffic. there is a small gravel side road you need to get on. You can't take a bike on a bus out of seville airport (we tried) but you might manage if it was in a box or bag.
you could follow this route:https://ridewithgps.com/routes/25926090
and Guillena has an albergue http://albergueluzdelcamino.es
and a hotel
so that would save you a day
as for distances, some of the plata is muddy roads, some mud track, some is good road. you might do 30k some days in hilly terrain in bad weather. I don't think we did 100k on more than a couple of days.
and if you buy the guide, it shows the green section for bikes and red for walkers: the red section can be bloody tough on a bike. DAHIKT.
en route be aware that many albergues open at 2pm and already have a queue of walkers outside waiting to check in. so your days might be pretty short cos you might want to be in that queue at 2pm.
most albergues will chuck you out at 8am and some walkers will be charging around the dorm aiming to get moving at 6am.
albergues can be €7, privately-owned are about €12 so if there are two of you it is feasible to share a hotel room which can be had for €35 or €40.
breakfast is extra.
on arrival in santiago you could do as we did and ride straight to the airport, stay in a hotel one night and get the flight in the morning.
i've been to santiago before so this was OK by me. but you might want to see it and go to the cathedral for the pilgrims' service.
also we had a few short days. so it should be possible to do it in your timescale.
the risk is that you have bad weather or a mechanical and lose a day or two. in that case you could put the bike on a bus (it's fine, it's €10 per bike ticket plus your ticket, wrap it in a plastic bag you can make that from bin liners and parcel tape).
you may be fitter and stronger than us.
we used this book:http://www.bicigrino.info/tienda_virtua ... 95269.html
we found the maps very accurate, the info useful and generally would have had a hard time without it. you can also download a GPX track of the route (which we found really very useful indeed) from that organisation. thoroughly recommended.
finally, to get home you can pay €100 for a box and put the bike in it and it arrives at your house in a week-ish. less stressful than flying with the bike, but it does mean you need to ride into santiago and deal with the shop. you can then fly home with only hand luggage - cos the sharp, pointy stabby metal things can go in the box.
another option is to get the boat to santander and ride through the picos de europa to leon and follow the camino to santiago. that took two weeks.
some days will be very hilly, Spain can get really hilly esp in Galicia when you'll be at your most tired. And it can rain in Spain when it wants to. In Galicia in October three years ago we lost half of one day then all the next holed up in an albergue while we watched the torrential rain pouring off a barn roof before being blown upwards into the air by the wind. In April the albergues are likely to be fairly empty and the weather dry and sunny. It's a good time to go: remember easter is in april this year. you might need to stock up on reserves of food before then, just in case.
And in some albergues cyclists are supposed to wait until about 7pm before they are allocated a bed so allow walkers to have priority. But this has never happened to me.
And if you go for hotels this doesn't apply: hotels can be booked the night before using email (there's wifi all over the place out there and you can use your UK data allowance there as well, because of our wonderful EU).
I think that's about everything.
any questions, PM me, I'd be happy to help.
I won't send yo my plata guide as i'm thinking of riding it myself, again, in April, but taking three weeks cos I'd like to chat to people.