David Hearn wrote:

Doesn't the Scottish system require surveys to be done prior to offer?

Not as such. The traditional method did in fact involve potential
buyers doing surveys first and then making a virtually unconditional
offer, taking a risk of having wasted the survey fee if someone else's
offer is accepted instead, and the risk is of course greater the more
buyers are bidding for one property.

Or
is it that the agreement to purchase (which is binding) can be broken if
the survey throws up a problem?

It doesn't work like that. Once an agreement is in place (i.e. an
unconditional offer has been unconditionally accepted), then that's
that. It can be broken, but then severe penalties come into play.

In fact all offers are and have always been conditional, with a
long list of ifs and buts, most of them standard and uncontroversial,
but the practice has been catching on of slipping a satisfactory survey
in as one of the conditions. Such offers are pretty well incapable of
being unconditionally accepted, but what tends to happen is that they
can be accepted subject to the condition being deleted. This then gives
the buyer a day in which to get the survey done and make up his mind,
and modify his offer by deleting the condition.

This tends to work well if you're the only buyer in the running.
For when a closing date for competitive bidding is set, the competing
offers may have deadlines for acceptance on them, and a seller will
obviously give preference to a higher but conditional offer over a
lower unconditional one only if the perceived risk of losing both
is low.

There is also the "Surveys On Line" scheme where the survey is
initially commissioned by the seller, and the buyers can buy a
copy cheaply if they agree to pay the full price if they buy the
property. But this is the more expensive homebuyer's report. If
you only want a basic valuation and cursory inspection, you may as
well pay for it.

Also, because of the Scottish system of sealed bids, you commonly have to
bid signficantly more than the asking price to try and get it.

That's OK. You bid what you think it's worth.

Depending on the deadline for offers, you could be sitting around
for 2 weeks or so to hear if your bid is accepted.

Unlikely. You can put an acceptance deadline on your offer, and
if the offer is high enough, the seller is under pressure either to
wait around for a higher one or to accept. Often he'll accept on
the spot, or, if enough other interest has been expressed, announce
an early closing date.

In this country, you can
generally get a response in a day or so letting you know either to
increase your offer, or consider other properties.

That is normal here too.