In a PDF I downloaded (Examples of U-value calculations using
BS EN ISO 6946:1997)

I find a table "Surface resistance for roofs, walls, and exposed floors
m^2K/W".

Heat flow direction Upwards Horizontal Downwards
Inside resistance 0.10 0.13 0.17
Outside Resistance 0.04 0.04 0.04
Underfloor space - 0.13 0.17


Is the difference between inside and outside just that wind
is assumed to be blowing across the outside?

Ian Stirling wrote:

In a PDF I downloaded (Examples of U-value calculations using
BS EN ISO 6946:1997)
I find a table "Surface resistance for roofs, walls, and exposed floors
m^2K/W".
[...]
Is the difference between inside and outside just that wind
is assumed to be blowing across the outside?

Yes, although the figures you quoted are somewhat different from the
ones I'm familiar with (from BRE Digest 108):

Heat flow direction Upwards Horizontal Downwards
Inside resistance 0.10 0.13 0.17
* 0.10 0.12 *0.14*
Outside Resistance 0.04 0.04 0.04
* 0.04 *0.06* 0.04
Underfloor space - 0.13 0.17
* *0.22*

See also building regs. Approved Document L1 for up-to-date tables of
U-values and calculation methods.

--
Andy