SELECT * FROM Table WHERE TRY_CONVERT(uniqueidentifier,Column) IS NULL

CREATE FUNCTION dbo.isuniqueidentifier (@ui varchar(50))  
RETURNS bit AS  
BEGIN

RETURN case when
    substring(@ui,9,1)='-' and
    substring(@ui,14,1)='-' and
    substring(@ui,19,1)='-' and
    substring(@ui,24,1)='-' and
    len(@ui) = 36 then 1 else 0 end

END

WHERE Column NOT LIKE  REPLACE('00000000-0000-0000-0000-000000000000', '0', '[0-9a-fA-F]')

DECLARE
@Table TABLE ( x tinyint )

BEGIN TRY
INSERT INTO @Table
SELECT 1
UNION
SELECT 2
UNION
SELECT 'a' 

END TRY
BEGIN CATCH
PRINT Error_Message( ) 
END CATCH