@Electric Sparrow, I walked the Inglès during Semana Santa ( the week leading up to Easter) last year.
It was VERY full. The week prior forum members were reporting meeting 10 or 12 fellow pilgrims per day. I started on the Monday with approximately 100 - 120 fellow pilgrims. Fortunately I had pre-booked everything, both at Pontdeume and Bruma those who had not and who arrived a little later in the day (after 14.00) struggled to find beds. In Bruma many had to taxi or walk an additional 10 kilometers, the que outside the municipal exceeded capacity at 11am. It's a very well known pinch point and options are limited. The hospitalero in Bruma advised me that it is the busiest period outside of the middle of July.
I'm not trying to scare you, just make you aware. If you were to walk the week afterwards you would almost certainly not need to book. Although as Janet mentions, booking a private room maybe more economical.
The vast majority of the pilgrims were Spanish, and looking to reach Santiago on Easter Friday. I met approximately 20 individuals over the four and a half days that spoke reasonable/ fluent English, 10 of whom were Portuguese, German, Dutch and Israeli.
The parade in Ferrol on Sunday evening was amazing, all of the pilgrims were in high spirits, and arriving into Santiago with all of the celebrations was extremely memorable.
All accommodation, cafes and restaurant options were open (it's a busy week for them).
As to lengthening the route you may find this helpful:
https://www.caminodesantiago.me/community/threads/lengthen-camino-ingles.79846/post-1125740