as though

Como si requires the imperfect or pluperfect subjunctive.

sat

Distinguish sentarse 'to sit down' and estar sentado 'to be seated'.

for

There are two basic possibilities in Spanish (look up time expressions). 'They had sat for fifteen minutes' = Hacía quince minutos que estaban sentadas / Llevaban quince minutos sentadas.

hope

Esperar takes the subjunctive.

feel

A reflexive is needed: sentirse.

ever

Not necessary to translate this reinforcing word, though algún día could be used.

send away

This is difficult, since Spanish does not have a verb that renders this notion unequivocally. Enviar and mandar are not enough on their own, but require a prepositional phrase with a. Rechazar and echar are too strong. It is probably better to adapt the sentence in the light of later information: ¿Por qué me mandasteis a vivir a casa de Huw y Susan...?

grit one's teeth

Apretar los dientes is the literal translation and is appropriate here.

glance

No simple equivalent (see also stare): echar(le) rápidas ojeadas / miradas, perhaps.

stare at

ahead

Use a preterite here, since it is an event in a sequence.

afraid

This is conventional fear, not real fear, so use temerse + indicative rather than temer + subjunctive.

cope

pull out

Not easy: the sense is se desvió bruscamente (para adelantar). Not cambiar de sentido!

overtake

get rid of

Deshacerse de or librarse de is the sense here.

if

This is a past conditional which is contrary to fact, and needs an pluperfect subjunctive after si and a conditional perfect in the main clause.

loved it

A lot of possibilities: lo pasabas muy bien en la finca / te divertías mucho en la finca / te encantaba estar en la finca

ask

Distinguish preguntar 'to ask (a question)' and pedir 'to ask (for)'.

turn to